Fragrance is used in a variety of products to enhance the consumer's delight in using those products. The desirability of producing products which retain their scent for an extended period of time after application to skin, scalp or hair, has long been recognized. Despite many efforts in this direction, most commercial products for skin, scalp and hair have an intense, pleasant odor initially but, disappointingly, tend to lose their scents within minutes after being applied. Attempts made to solve the problem include using inorganic carriers impregnated with fragrance for incorporation into products. EP 0 332 259A discloses perfume particles made by adsorbing perfume onto silica. U.S. Pat. No. 5,336,665 discloses free-flowing hydrophobic porous inorganic hydrophobic carrier particles, such as aluminosilicates, having a certain pore volume and pore diameter and having perfume adsorbed into the particles. A fragrant material composed of aggregates of sodium chloride granules and having a fragrant oil absorbed in the pores between granules is disclosed in U.S. Pat. No. 5,246,919.
Efforts have been made to increase the amount of time that fragrances remain on keratinous surfaces of the body without increasing fragrance load, such as by the use of coatings and microencapsulation systems. A fragrant bead composition made up of a multiplicity of prilled urea beads having an adherent surface coating containing a fragrance is described in U.S. Pat. No. 4,020,156. A discontinuous surface coating for particles which permits a controlled release of actives from an underlying deposit on a core particle is described in U.S. 2006/0153889.
Microencapsulation technology is well known in the art and is generally directed to encapsulating core materials that require protection until time of use in a protective covering. Generally, a high viscosity fluid will be dispersed more slowly from a carrier which tends to extend fragrance duration, while a lower viscosity fluid will enhance the intensity of the scent by virtue of a higher evaporation rate. Time release microcapsules release their core materials at a controlled rate. The result is that the encapsulated material has a longer effective life since it is not immediately released from the protective microcapsule. A polymeric encapsulated liquid fragrance which is further treated with a cationic polymer to improve deposition is described in U.S. Pat. No. 7,294,612. A pre-glass agglomeration of fused microspheres uses microcapillary action to quickly uptake oil-based or alcohol-based liquids to more than double the weight of the pre-glass agglomeration, as described in U.S. Pat. No. 6,245,733. A cosmetic material encapsulated by a frangible capsule of thermo-softening material that is solid at room temperature but which will rupture when the composition is rubbed on a skin surface and melts up on application to the skin is described in U.S. Pat. No. 7,622,132.
Notwithstanding the above, there is still an ongoing need for fragranced products which demonstrate an extended duration of continuous release of fragrance to the skin, scalp and hair, over extended periods of time.